Acta Bot. Need. 28-35. 23(1), February 1974, p.
Notes on entomogenous fungi from
Ghana.
II. The genus Akanthomyces
R.A. Samson and H.C. Evans
Centraalbureau voor Schimmelcultures, Baam and Cocoa Research Institute, Tafo, Ghana
(present address: Estacion Experimental Tropical, Pichilingue, INIAP, Apartado 24, Queve-
do, Ecuador)
SUMMARY
Four species of Akanthomyces, collected onvarious arthropod hosts in Ghana, are described
and illustrated. to Akanthomyces gracilis Samson & Evans spec. nov. appeared occur on a
wide variety of insect hosts and is particularly common on ants. ikanthomyces pistillariae- formis (Pat.) Samson & Evans comb. nov. (= Isaria pistillariaeformis Pat.) is often found on
moths together with Cordyceps tuberculata. The variability in synnematous habit and the
associated Cordyceps tuberculata is discussed. Akanthomyces arachnophilus (Petch) Samson &
Evans comb. nov. (= Trichosterigma arachnophilum Petch) was collected twice on spiders
with Torrubiella Mains is rather together flava Fetch. A. aranearum (Petch) common on
spiders.
INTRODUCTION
Lebert revised The genus Akanthomyces was by Mains (1950), who charac-
terized it covered of by cylindrical synnemata by a hymenium-like layer
phialides producing one-celled catenulate conidia. Species with clavate synne-
mata and a sterile stipe were placed in the genus Insecticola Mains. This synne-
matous habit does not allow a clear delimitationbetween Akanthomyces and
Insecticola, since clavate as well as cylindrical synnemata, with or without sterile
stipes, occur within the same species (e.g. Isariapistillariaeformis Pat.).
In the Akanthomyces species accepted by Mains (1950) the phialides are of
different shapes. In A. aranearum they are cylindrical without distinct necks,
while in A. aculeatus they are more or less flask-shaped, tapering to a short neck,
thus resembling the conidiogenous structures of the genus Paecilomyces
is Bain.. However, the genus Akanthomyces separated from Paecilomyces by
the typical hymenium-like arrangement of the phialides. In Paecilomyces these
Akantho- structures are loose and verticillate. The conidiogenous structures of
myces are also somewhat reminiscent of the genus Nalanthamala Subr., which
is sporodochium-like and not known to be entomogenous.
various Four species belonging to Akanthomyces were regularly collected on
arthropod hosts in Ghana. New combinations are proposed for two species
originally described in Isaria and Trichosterigma (= Hirsutella). One species
differs sufficiently from theknown taxa to warrant describing it as new. NOTES ON ENTOMOGENOUS FUNGI FROM GHANA II 29
Akanthomyces gracilis Samson & Evans, spec. nov. - Fig. 1, a-b; Figs. 2-6.
Syrmemata in insectis dispersa vel aggregata, alba ad flavobrunnea,plus minusve pulverulenta, cylindrica, plerumque simplicia, nonnumquam ramosa, longitudine variabilia, 0.7-2 mm x
100-400 ad 3 0.5 Phialides dense gun, nonnumquam cm longa et mm crassa. aggregatae,
synnema in strato tegentes, leves, parte basilari cylindrica in collum tenerum attenuata,7-10
1.5-2.5 Conidia catenis vel fusi- x gm. continua, longis connexa, levia, hyalina, ellipsoidea formia, 2.5-3 X 1-1.6 gm.
Typus CBS 141.73, isolatus e Paltothyreo tarsato, Atewa Forest Reserve, Ghana.
Synnemata on the insect hosts scattered to crowded, arising from the natural
body openings and intersegmental and appendage joints, usually white to
less but yellow-brown, more or pulverulent, cylindrical, usually simple some-
times branched, variable in size, according to the insect species and locality
usually measuring 0.7-2 mm X 100-400 pm, occasionally up to 3 cm in length
and 0.5 mm in diameter. Phialides densely compacted into a layer covering the
synnema, consisting of a cylindrical basal part tapering to a slender neck, 7-10
1.5-2.5 smooth-walled. Conidia in smooth- X pm, one-celled, long chains,
walled, hyaline, ellipsoidal to fusiform, 2.5-3 X 1-1.6pm.
1 Colonies on mealworm-agar growing moderately fast, attaining a diameter
of about 5 cm within one month at 25 °C, consisting of a white to creamish
mycelial basal felt, from which numerous conspicuous slender synnemata arise
Fig. la, b. Akanthomyces gracilis: a- part of synnema, b. conidia.
d. of d. conidia. Fig. 1c, A. pistillariaeformis; c. part synnema,
1 contains of 200 dried 20 20 Mealworm-agar an extract g ground mealworms, g sucrose, g
agar and 1000 ml water. 30 R. A. SAMSON AND H. C. EVANS
in concentric developing rings, usually densely grouped towards the centre, sometimes intermixed with loose conidial structures. Synnemata positively phototropic, at first white, later becoming yellowish and pulverulent, cylindrical
in sometimes 2 35 in to slightly clavate, age branched, measuring to mm length and 0.1-0.5 mm in diameter, composed of smooth, longitudinal, hyaline hyphae. Phialides and conidia as on the natural substrate. Perfect state or chlamydospores not observed.
Colonies malt oatmeal on PDA, or agar as on mealworm agar, but growth thinner and synnemata less numerous.
Materialexamined; living cultures
CBS 141.73, type culture, isolated from Paltothyreus tarsatus (Fabr.) collected in Atewa Forest
Reserve (Ghana) (Herbariumspecimen with accession number Ras 0102 in herb. CBS).
CBS 740.73 and 741.73, isolated from Paltothyreus tarsatus (Fabr.) in Atewa Forest Reserve.
CBS 728.73 and 742.73, isolated from Cercopidae species oncocoa leaf, Tafo.
CBS 727.73, isolated from Lepidoptera larva on cocoabark, Tafo.
Herbarium specimens
Ras 0016 and Ras 0018 on Paltothyreus tarsatus (Fabr.) collected at Mt. Atewa and Begoro.
Specimens of this collection are associated with different Cordyceps spp.. Ras 0023 on Crema-
collected Mt. Atewa. Ras 0107 collected togaster spp., at on Callibaphus longirostris (Drury),
at Nobi Scarp Forest. Ras 0108 onMacromischoides inermis Bernard, collected at Mt. Atewa.
Specimens of this collection are associated with different Cordyceps spp.. Ras 0134 onPolyrha-
chis militaris (Fabr.), collected at Mt. Atewa. On the same host perithecia of a Torrubiella
species were observed. Ras 0135 on Camponotus brutus (Forel) (? alates), collected in Tafo.
Ras 0136 on Crematogaster bequarti (Forel), collected at Mt. Atewa.
Akanthomyces gracilis can be distinguished from the other species of Akantho-
its small to fusiform conidia and myces by ellipsoidal cylindrical phialides
tapering to a slender neck. The conidiogenous cells and conidia are reminiscent
of those of Paecilomyces farinosus (Holm per Fr.) Brown & Smith. A. gracilis
can be considered as an intermediate species between Paecilomyces and Akan-
thomyces; it is placed in the latter genus because of the hymenium-like layer of
the phialides and the distinct synnemata produced regularly on the insect as
well as on agar media. In synnematous Paecilomyces species the conidiogenous
and Furthermore the structures are verticillately loosely arranged. synnema
production in pure culture is usually lost after a few transfers.
also Fetch A. gracilis resembles Syngliocladium aranearum (1932b). In this
species conidia are small (1.5-2.5 x 1 globose to ellipsoidal and produced
conidia heads and by flask-shaped phialides. The are, however, produced in not
in long dry chains as in A. gracilis. NOTES ON ENTOMOGENOUS FUNGI FROM GHANA H 31
HOST LIST OF AKANTHOMYCES GRACILIS
Hymenoptera, Formicidae
Ponerinae: Paltothyreus tarsatus (Fabr.), Platythyrea conradti Emery
Formicinae: Polyrhachis militaris (Fabr.), P. monista Santschi, P. decem-
dentataE. Andre, Camponotus brutus (Ford), Oecophylla longi-
noda(Latr.)
Myrmicinae: Crematogaster bequarti (Ford), C. clariventris Mayr,
C. striatula Emery, Macromischoides aculeatus Mayr, M. iner-
mis Bernard
Dorylinae: Dorylus sp.
Coleoptera: beetlelarvae, beetleimago (adult)
Lepidoptera: moth larvae
Heteroptera, Pyrrhocoridae: Callibaphus longirostris (Drury)
Homoptera, Cercopidae: froghopper.
of insect hosts and is A. gracilis occurs on a wide variety particularly common
on ants. The biotopes of the host habitats are diverse and it is probable that this
pathogen is widely distributed throughout the tropics. The size and complexity
to be related to the size of the insect host and to the of the synnemata appear
habitat. Insects buried in soil, leaf litter or wood invariably bear very long,
complex synnemata, which ramify above or withinthe substrate.
Akanthomyces pistillariaeformis (Pat.) Samson & Evans, comb. nov. - Fig. 1,
c-d ; Fig. 7.
Isaria pistillariaeformis Pat. in Bull. Soc. mycol. Fr. 9: 163, 1893 (basionym) = Insecticola pistillariaeformis (Pat.) Mains in Mycologia 42:579. 1950.
Synnemata scattered, arising from different parts of the body, cylindrical to
clavate and stipitate, white to creamish, pulverulent, 1-6 mm in length and
in branched. 50-300 |tm diameter, simple, occasionally Mycelium white,
covering the insect and spreading onto the leaf surface. Phialides densely com-
the scattered at the pacted into a layer covering synnema, more or lacking base,
consisting of a cylindrical basal portion, tapering abruptly to a distinct neck,
smooth-walled. Conidia in short 7-10.5 X 2.7-3.5 [xm, chains, one-celled,
hyaline, smooth-walled, cylindrical to narrowly fusiform, 4.5-6 X 1.2-1.5
|i,m. Often associated with Cordyceps tuberculata (Lebert) Maire in Bull. Soc.
d’Hist. Nat. de 1’Afrique du Nord 7: 165. 1917, see also Fetch (1932a), Koba-
yasi (1941) and Mains (1958).
Material examined;
Ras 0031, 0032, 0061, 0124, 0125 and 0127 onmoths, collected at Mt. Atewa,Tafo, Kukuran-
tumi, Begoro. Specimens0124, 0125 and 0127 containingalso Cordyceps tuberculata.
Isaria pistillariaeformis Pat. (FH) type on moth, labelled „Tuente de Chimbo sent 1891,
Lagerh.” 32 R. A. SAMSON AND H. C. EVANS
Fig. 2-6. Akanthomyces gracilis
2. on Callibaphus longirostris (c. X 2),
3. on Macromischoides inermis (c. X 8.5),
4. on Palthothyreus tarsatus (c. X 3),
oatmeal 5. synnemata growing on agar,
6. mealworm agar culture showing zonated growth.
Fig. 7. A. pistillariaeformis on moth (c. X 5). NOTES ON ENTOMOGENOUS FUNGI FROM GHANA II 33
Examination of the Ghanian specimens and those identified by Fetch (in herb.
K) as Cordyceps tuberculata showed that there is a great variation in perithecial
Perithecia in intermediate form. are arranged loosely or stromata, while forms occur. Fetch apparently used the terms ”Cordyceps” - and ”Torrubiella”- form, probably to indicate the difference in stroma development. Similarly there is variation in size and great synnema shape. Long cylindrical pointed as well as short stipitate clavate synnemata were observed. The cylindrical synne- mata often occur on large moths, whereas the short clavate synnemata are associated with small insect specimens. On some specimens both extremes of synnema form occur. These observations showed the variability in Cordyceps tuberculata and the associated Isaria pistillariaeformis Pat. Accomodation of this species in Akanthomyces seems betterjustified than in Insecticola.
Akanthomyces arachnophilus (Fetch) Samson & Evans, comb. nov. - Fig. 8, a-b; Fig. 10.
Trichosterigma arachnophilum Fetch in Trans. Br. mycol. Soc. 8: 215. 1923 (basionym). =
Hirsutella arachnophila (Fetch) Fetch in Trans. Br. mycol. Soc. 9: 93. 1923 (and ibid. 10: 43.
1924).
Cream mycelial cushion completely covering very small spiders and spreading
the leaf fimbriate. onto surface; margin Synnemata erect, simple or branched, cylindrical, 2.5-5 mm X 50-75 jxm, creamish yellow to pale brown. Phialides in scattered a single layer, to crowded, consisting of a globose basal part,
distinct 3.2-4.3 6.5-8.5 smooth-walled. tapering abruptly to a neck, x [im, Conidia in short chains, one-celled, hyaline, smooth-walled, fusiform, 4.5-5.5
1.5-3 (-6) X j^m. Associated with Torrubiellaflava Fetch (1923).
b. Fig. 8a, Akanthomyces arachnophilus; a. part of synnema, b. conidia,
d. A. of d. conidia Fig. 8c, aranearum; c. part synnema, 34 R. A. SAMSON AND H. C. EVANS
Material examined:
Hirsutella arachnophila (Fetch) Fetch (K) type on spiders, Hakgala, Ceylon, March, 1922
Additional specimens collected in Ceylon, Feb. and Sept. 1923.
Akanthomyces arachnophilus (Ras 0109 A en B) on spiders, Begoro Forest Reserve, Ghana,
onunderside of leaves of rubiaceous shrubs.
The arrangement of phialides in a hymenium and the production of conidia in
chains the inclusion ofthis in the dry readily justify species genus Akanthomyces.
Fetch (1924 a and b) considered Torrubiellaflava Fetch to be the perfect
state of H. arachnophila, although the two stages were never found together on
of A. collectedin Ghana the same stroma. Two specimens arachnophilus possess
one to several yellow-brown ovoid perithecia attached laterally near the base
of the The fits that of Torrubiella and it would synnema. description flava seem that Fetch was justified in linking this with A. arachnophilus.
Mains- Akanthomyces aranearum (Fetch) Fig. 8 c-d; Fig. 9.
Mains in 42: = Akanthomyces aranearum (Fetch) Mycologia 574. 1950. HymenostUbe arane-
arum Fetch in Trans. Br. mycol. Soc. 16: 221. 1932.
A distinctive species, characterized by its verrucose phialides and obclavate conidia in short chains. The brown synnemata and verrucose phialides may
that this but A. is suggest species belongs to Hymenostilbe, aranearum separated basis catenulate conidia. from this genus on the of the Nevertheless the chains
short and and without sufficient material the are very fragile species may easily
be mis-identifiedas a HymenostUbe.
Fig. 9. Akanthomyces aranearum on spider (c. X 3.5),
Fig. 10. A. arachnophilus on spider (c. X 8.5). NOTES ON ENTOMOGENOUS FUNGI FROM GHANA It 35
Materialexamined:
Ras 0003 and 0133 onspiders collected in Begoro, Tafo, Mt. Atewa, Oyoko and Bunso.
in Dr. W. Gams collected A. aranearum on a spider Houdringen (Bilthoven), Netherlands
(WG 1522).
ACKNOWLEDGEMENTS
The authors thank Miss H. Pannebakker for making the photographs and Mr. L. P. S. van
der Geest for correcting the names ofsome insect species.
REFERENCES
Y. The and its allies. Sci. Bunrika Kobayasi, (1941): genus Cordyceps Rep. Tokyo Daig.,
Sect. B, 5: 53-260.
Mains, E. B. (1950): Entomogenous species of Akanthomyces, Hymenostilbe and Insecticola
in North America. Mycologia 42 : 566-589.
— (1958): Entomogenous Cordyceps from North America. Mycologia 50: 168-222.
Fetch, T. (1923): The genus Cladosterigma Pat. Trans. Br. ntycol. Soc. 8: 212-215.
— The Fetch. Soc. 9: 93-94. (1924a): genus Trichosterigma Trans. Br. mycol.
Br. — (1924b): Studies in entomogenous fungi III. Torrubiella. Trans. mycol. Soc. 10:
108-128.
— (1932a): Notes on entomogenous fungi. Trans. Br. mycol. Soc. 16: 209-245.
— (1932b): A list of the entomogenous fungi of Great Britain. Trans. Br. mycol. Soc. 17;
170-178.